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When do you give up on a Navigator Sensor?

Discussion in 'Continuous Glucose Sensing' started by zatff, Jan 24, 2010.

  1. zatff

    zatff Approved members

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    My current sensor has been in 46 hours. It doesn't give any readings, just the three dashes. Every time I check my BG with a finger stick, it says calibration failed. Please test again later. I have had sensors take 30 hours to start giving readings after several reports of failure to calibrate. Usually they start working around 18 - 20 hours after insertion and three or four attempts to calibrate. My last one was really good and started on second try. Unfortunately the transmitter battery died in 24 hours but i was able to restart it after I replace the battery and it started the second time too around 14 hours. It also gave me excellent readings for next five days, which for me only happens about a third of the time.

    At what point should you give up on a sensor and figure it just won't work.
     
  2. Nancy in VA

    Nancy in VA Approved members

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    The key to it is you need to make sure you plan the 10-hour and 12-hour calibrations when you know you will be stable. We tend to check about 1 hour ahead of when the calibration is due to come, using our OneTouch and treat a low or a high conservatively. I target to be no higher than 120 - 140 on the first calibration and BY NO MEANS under 100 on the 2nd one. I have found if you are over 100 on the 2nd one, it will probably ask for calibrations every 1-2 hours for the next 6-8. It doesn't seem to like to calibrate too low.

    I was talking with my CDE's husband, who wears a Navigator. He often has a similar struggle to you. But I still say the best way to get it going is know enough about your BG patterns to know when the right time to plan the calibration is. For us, its best to plan for a 4pm / 6pm calibration start, with dinner after 6pm. That's a 6am insertion.
     
  3. BrendaK

    BrendaK Neonatal Diabetes Registry

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    Have you tried calling Abbott? We rarely ever have trouble calibrating, even when not stable! I bet it really depends on the quality of the transmitter as well, I think we lucked out and got a good one. Definitley call Abbott when you have some time and they can walk you through troubleshooting steps.
     
  4. Rachel's Dad

    Rachel's Dad Approved members

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    If you get sensor error 15 for the initial calibration it can take up to 4hrs to settle(it will ask for a cal every 60minutes). Always wait for the receiver to prompt you to calibrate and make sure that the battery levels are 75-100% when starting/restarting. I also call the help line with any questions.....they can be very helpful. We start a new sensor at 9pm so that BS levels are flat when we cal at 7am. I hope this helps......
     
  5. buggle

    buggle Approved members

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    We find that telling it to reconnect every once in a while usually brings it back -- not necessarily right away, either. I've learned not to give up on them and to just check an hour or two later after getting the dashes across the screen. And often, once it kicks in again, it'll keep working. I don't know why they get so touchy sometimes, but they almost always recover for us.
     
  6. zatff

    zatff Approved members

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    To my surprise it started working around 48 hours. I was just getting ready to replace it. It worked for about 5 hours and then went back to dashes for eight hours and then it kicked in again and has worked for 13 hours. Some of the readings were right on and some were way off like a 56 when I was 112. It is frustrating though to have it be so erratic. I have less than two days left before it expires so if it works till the end of that time I will have about 2 1/2 days of readings and some of those are way off. At the price we pay for these sensors we should be able to get at least four days of readings from one. If I try reset it and it takes i could get 4 or 5 days out of this sensor yet.
     
  7. selketine

    selketine Approved members

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    When they are "way off" are they low or high or both? For us, way off low means the little sensor thing that goes in the skin isn't in deep enough - it is coming out.

    I've never had the problem you've had except when the sensor piece wasn't into the skin the way it should be. If that is happening routinely then I'd call Abbott and talk to them.

    It could be a transmitter issue. I also agree that you have to be really careful with those first two calibrations - at least in our experience. We get MUCH better results if he is between 90-150 or so (not above 180 though that is still pushing it).
     
  8. zatff

    zatff Approved members

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    For me the errors generally are the receiver is reading way too low, less than half of actual BG level. Right now is says 74 when finger stick indicates 164. Last night it said 66 when I was at 90. I have had it go down in 20's and 30's and stay at that level for hours and then it will sometimes return to giving accurate readings. Abbott tech support told me on my last call that since it had only been giving me readings in 30's for a few hours I should wait and it might start working again and that time it did about 24 hours later.

    Early this morning is was right on within 10% of BG finger test. The sensor has 29 hours to expiration and I often get erroneous readings close to expiration.

    The trouble calibrating doesn't seem related to changing BG levels. My first four BG levels over a six hour period were all in 130 range which should be ideal for calibration. Sometimes when I get lucky with a good sensor it will calibrate early even though there are 150 point swings between readings.

    I think your point about sensor not being deep enough could be true. I have not had these problems with the few Dexcom sensors I have used but they have a longer probe and go in at an angle and that just might be better match for me.

    Even though I have had numerous problems with the Navigator system it has been helpful in getting rid of most of my hypos that I was having without any awareness till I got the Navigator CGM. As others have stated, any CGM is better than none as it encourages you to test more often so you have more info on what your BG actually are doing.
     
  9. Nancy in VA

    Nancy in VA Approved members

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    Where are you wearing the sensor? Are you wearing it with the sensor "up" and the transmitter at least angled down, if not straight down? I understand that can affect how it reads.
     
  10. zatff

    zatff Approved members

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    Right, that is how the trainer told me to insert it.
     
  11. selketine

    selketine Approved members

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    I really think the sensor is pulling out of the skin - maybe going in and out so it refuses to give readings because the data is so confusing to it.

    Do you insert your own sensor? We use the back of the arm for my son - perhaps have someone insert it on the back of the arm for you? Just wondering if that would make a difference. Perhaps having someone else try inserting it would get a straighter or deeper insertion. I'm just throwing out ideas there....

    If the tape is loose at all it could cause the sensor to not stay in - this is sometimes what happens to us towards the end of the 10 days - the tape is getting loose and we get a lot more errors and the dashes with no readings for long stretches.

    I would ask them to send another transmitter if all else fails. Ask them to have a trainer come out to help or to assist you via phone at insertion and calibration so they cannot blame you for it not working.
     
  12. sneakermom

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    We will sometimes get the 3 dashes when we are having trouble with the signal. For us, that seems to be for 2 reasons: (1) the battery in either the receiver or transmitter is weak or (2) the sensor is coming dislodged. I will be patient to a point when I'm getting sporadic signals. Usually once it starts for us, we continue to get sporadic intervals without data until we change the sensor and/or battery.
     

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